Fuel injection pump



FUEL. INJECTION PUMP Filed April 15. 1948 GEORGE STEVEN ROY R. FRUEHAUFIN VEN TORS Patented Dec. 30,

FUEL INJECTION PUMP- George Steven, Kenmore, andRoy R. Fruehauf. OrchardPark, N. Y., assignors to Worthington Corporation, a corporation ofDelaware Application April 15, 1948, Serial No. 21,246

13 Claims.

1 This invention relates to liquid fuel injection apparatus and, inparticular, refers to fuel pumps providing pilot injection. Thisapplication is a continuation-in-part of application No. 709,514

filed November 13, 1946 now Patent No. 2,612,842

dated .October 7, 1952.

Though it will be obvious that it is not so limoil into the engine.

It has been found that the characteristics of the gaseous fuels in thistype of engine are such that a pilot charge of injection oil is requiredfor ignition. Since this charge is quite different than that requiredwhen the engine is operating principally on fuel oil, it has been foundpreferable to provide a separate pilot injection system for use when theengine is operating on gaseous fuels. It is clearly desirable toeliminate this separate system if it can be done without sacrificingoperation, and an object of the present invention is to do so bycombining the pilot system with the system used for regular injection ofoil fuel.

When the dual fuel engine is switched to operation 'on oil fuel, bysuitable means such as disclosed in said patents, it becomes essentiallya dieselrtype engine. Similar problems are encountered, therefore, andone of these is noisy combustion or knocking. It may be said in ,generalterms that this is believed to be caused by an excessive quantity offuel having been injected into the cylinder, before ignition begins.This is referred to as ignition lag.

It has long been believed that this knocking" could be controlled byproviding pilot injections of small quantities of fuel oil. When theseig nite, they donot cause knocks but still generate sumcient heat toignite the main charge of fuel which follows. Thus, with regard to themain charge, there is reduced ignition lag." Total fuel injection inaccordance with this-method therefore consists of two stages, first thepilot charge and then the main charge.

Control of the quantity of fuel injected in each stage is clearlydesirable. This can, of course, be accomplished by two separate systems,one for pilot injection and the other for mairi injection. Such anarrangement, however, has the disadvantages of being imnecessarilyexpensive .and complex to manufacture and operate. Fuel pumps have,therefore, been developed which. provide both pilot and main injection,through one injection nozzle.

Considering the reciprocating plunger type of fuel pump, the rate offuel injection is dependent upon the effective area of the piston andupon the velocity. with which it moves; and the total quantity injectedis dependent upon the area of this piston and the effective length ofthe stroke. I In prior art fuel pumps, quantity control has centeredabout regulation of velocity and time. Thus, cams are often used to varythe velocity of the plunger. For pilot contro1 cams are designed to givea low velocity and therefore a small quantity of pilot fuel during thefirst or pilot stage. During the main stage, the cams increase thevelocity to provide for a large charge. Cam

control has not, however, been entirely satisfactory because of theextremely critical dimensions required of the cam surface. Because ofthe effects of wear and machining inaccuracies upon the cam surface, ithas been almost impossible to obtain optimum and dependable injectioncontrol.

Another method of control which is embodied in prior art fuel pumps isthat of the length of the stroke. This is used in the interruptedinjection type of pump, for instance, where the plunger has a shortstroke for pilot injection whereupon thefuel is bypassed for a briefperiod and then a longer, main stroke occurs. It will be recognized thatunless this bypass control is combined with a. cam that only the totalquantity injected, and not the rate of injection, is controlled. When itis combined with a cam to control the rate, it adds the disadvantagesjust mentioned and still has its own feature of interrupted ordiscontinuous injection which is often undesirable.

It is an object-of the present invention to provide a fuel pump which,in general, is not subject to the disadvantages of the prior art devicesand which, in particular, has two rates of injection, a pilot rate and amain rate, which are not basically controlled by cams or bypasses.

When the fuel pump is used on a dual fuel engine which is operating ongaseous fuel, the main charge is not required and it is, therefore, anobject of the invention to provide a fuel pump having two injectionstages, one of which may be rendered inoperative.

3 in contrast to the prior art referred to, the present inventioncontemplates control of the rate of injection by means of the pistonarea. In

. order to provide two injection stages, the present invention has twopistons of different areas. The piston of smaller area is used for thepilot injection. A feature of the invention makes it possible touse'both pistons for the main charge. It will thus be realized that theinvention provides a relatively slow rate of pilot injection and a highrate of main injection. Means are also provided to connect the mainpiston to a low pressure area so that its effective stroke can be variedfrom a maximum when the engine operates entirely on oil fuel to zerowhen the engine operates entirely on the channel 23 is in line with thehole 'or suction opening I no oil will be discharged from the cylinder36 as it will always be connected with the suction chamber 1 through thehelical channel and the channel or cut-out 23.

According to the present invention means for a second rate of injectionis added to the foregoing structure which may be of the well known Boschdesign, as indicated. This means includes the upper housing I which isconnected in fluidtight relationship to the liner II by the ground jointand to the housing 3 by the soft gasket 30 and the bolts 32. Thishousing has a bore 34 which is coaxial with the liner bore 5. Ifdesired, the lower end of this bore may be adapted as shown to form anextension of the liner 6 bore 5 above the plunger 2|, this total spacebelower housing 3 and related elements may, if

desired, follow the design of the Bosch injection pump which is wellknown in the art. Thus, the housing 3 has a longitudinal bore 5 openinginto a larger suction chamber 1 near the top of the housing. The chamberI is connected to a source of fuel oil by means of a passage or conduit9. A liner II is mounted. in the bore 5 and extends through the suctionchamber I so that the top thereof forms a part of the top of the housing3. The liner II has holes I3 and I5 in its walls which connect theinterior of the liner to the suction chamber 1. The axes of these holespreferably lie on a diameter of the liner.

The plunger or piston 2| is reciprocably and rotatably mounted in theliner I I. This plunger 2| has a helical cut-out 25 connected to the topof the plunger by a longitudinal slot 23. Means are provided to rotatethe plunger 2| and consist of a rack I3 operating on a gear IT. The gearIT is formed upon the sleeve I1. The sleeve H has slots I I in its lowersection in which arms 2| are guided. The arms 2| are formed upon orcarried by the plunger or piston 2|. This construction is well known inthe art and is employed in the well known Bosch fuel pumps.

The operation of the plunger or piston 2| is similar to the operation ofany fuel pump of this general type. As the plunger or piston 2| movesdownward to its lowest position (as shown in the drawing) oil flows intothe cylinder 36 through the holes or suction openings I3 and I5 in theliner II and fills the cylinder 36. As the plunger or piston 2| movesupward oil is discharged through the holes or suction openings I3 and I5until the top edge of the plunger or piston 2| covers these openings.Pressure then rises in the cylinder 36 and oil is discharged throughtheport 58, check valve 60, passages 54 and 56 and fuel line 50 to theengine (not shown). Oil continues to discharge until the hole or suctionopening I5 is uncovered by the helical cutout 25 in the plunger,releasing the pressure in the cylinder-36 to the suction chamber 1through the channel 23 and helical cut-out 25 and the hole or suctionopening I5. Rotation of the plunger or piston 2| changes the relativeposition of the helix and the hole I5 and varies the point in the strokeof the plunger or piston 2| at which the hole or suction opening I5 isuncovered and thus varies the amount of oil discharged. If the plunger2| is rotated until between. A loose T and slot connection 40 is shownfor this purpose though any suitable means may be used. The piston orplunger 38 is preferably made of two sections which are threadablyconnected together as shown at 42 thus making it possible to vary thedistance between the top of the piston or plunger 38 and the top of theplunger or piston 2|, or any other suitable means may be used.

The upper part of the bore 34 is enlarged to receive a spring loadedcheck valve 44 which prevents fiow toward the piston 38. An adapter 46is threaded into the top end of the bore 34 and has a through hole 48connecting the bore to the fuel pipe 50 which is connected to the pumpin a suitable manner as by the union 52.

The upper housing I has a second and nonaxial bore 54. This bore isconnected by a passage 56 to the bore 34 above the check valve 44 and tothe top of the cylinder 36 by a passage 58. A spring loaded check valve60 in the bore 54 prevents flow therefrom into the cylinder 36 throughthe passage 58.

The bore 34 receives oil from the suction passage through a passage 62.The opening 64 of the passage 62 is positioned so that it is uncoveredwhen the piston or plunger 38 is in the lower portions of its stroke.The housing may have another passage 66 which opens at one end into thecylinder 36 and at its upper end 68 into the bore 34 below the opening64. The piston 38 has an annular groove 10 which is adapted tocommunicate with the opening 68, the groove I8 being connected to thetop of the piston and. thus to the open portions of the bore 34, bymeans of a suitable passage 12 in the piston which opens out of the topthereof.

When the fuel pump is used on a dual fuel 4 engine operating solely ongaseous fuel, the rack I9 andgear II mechanism are actuated, manually orby a suitable automatic means such as shown in the aforesaid patents toBarnaby et al. and Miller et al., to rotate the plunger 2| so that theplunger slot 23 is in alignment with the hole I5. When this is done, thetop of the plunger or piston 2| is always connected to the suctionchamber 1 so that this plunger will not pump oil stantially above thatin the suction line 8.

absence The plunger II and piston or plunger 33 are reciprocated by anysuitable means (notshown) which may include a cam. n the down stroke oilis drawn into the cylinder 38 through the hole lland into the bore 34through passage 82. On the upstroke the oil in cylinder 38 is by-passedto the suction chamber 1 as already-mentioned. On

the upstroke the oil in the cylinder 34 is discharged through the port84 tothe suction chamher until the plunger covers the port 34. The

pressure of the oil in the cylinder 34 then is increased by upwardmovement of the piston or plunger 38 until it is sumcient to'open checkvalve 44. Further upward movement causes oil to be discharged throughthe line 50 into the engine (not shown). When the piston or plunger 38rises to the point where the annular groove 10 communicates with thehole 58, the bore 34 is connected to the suction chamber 1 through thepassages 12 and 68. The check valve 44 therefore closes and pilotinjection ceases.

. When it is desired to operate on two stages. i. e., pilot charge andthen a main charge, the

of pilot fuel can be varied by varying the distance between the top ofthe piston or plunger 34 and the relief 18. The total quantity of maincharge can be varied by changing the effective stroke of the plunger 2|also. This is done by rotating the plunger or piston 2| to vary therelative rotary position between the helical groove 25 and the hole l3.Rotation of the plunger 2| in one direction lengthens the strokealigning the hole II with a point on the upper helicalboundary of thegroove 25 which is more remote fromthe top of the plunger 2 I. Therotation of the plunger II in the opposite direction has the oppositeeffect.

The relative timing of the beginning of injection of oil by the pilotplunger. 38 and the main plunger 2| may bevaried by means of the thread-7 ed connection 43.

piston or plunger 2! is rotated so that the slot 23 is not in alignmentwith the hole IS. The opening 84 and the holes i3 and i5 may beposi-tloned so that in the down piston or plunger position the openingis closer to the top of piston 38 than the holes l3 and I! are to thetop of plunger or piston 2i. With this arrangement, the piston orplunger 38 will close its connection to suction first and start to pumpbefore the plunger or piston II to provide the pilot injection beforethe second stage injection occurs. The differential between these twopositions can be varied by means of the threaded connection 43 whichwill raise or lower the piston 38 with respect to opening 64 so that byvariation of the relation of the ports 64 and I3 the beginning ofinjection of oil, or pumping by the piston or plunger 38 will be withrelation to the beginning of pumping of oil by the plunger or piston 2|.When the plunger or piston 2| rises to the point where it covers holesl3 and I5, it will force oil out'of cylinder 38 through passage 58 andby check valve 68 into the bore 54. Oil flows from the bore 54 throughpassage 56 into the upper part of bore 34 above the check valve 44 andis forced to the engine through line 58. It will be recognized that theoil flowing through line so at this point in the second stage consistsof oil from bore 34 and oil from cylinder 36. When the piston or plunger38 rises to the position in which the groove 10 and passage 82 connectsthe bore 34 to cylinder 38, then oil from cylinder 38 will still beforced into the line 50 by both the piston or plunger 38 and the plungeror piston 2i as it can no longer by-pass to cylinder 33 since thepressure therein is substantially the same as the pressure in cylinder34. Discharge of oil oontinues until the groove 25 on plunger or piston2| comes into alignment with the hole i5. This connects the cylinder 36through the slot 23, helical groove 25,.and hole IS with the suctioncham The novel underlying principle of the present invention issufiiciently broad to include and suggest many modifications of theparticular details of construction herein described and shown in thedrawing, and it is to be understood that the scope of the invention isnot confined to the details shown and described but is limited only bythe appended claims.

What is claimed is:

i. In a fuel injection pump, a housing having first and second bores ofdifferent diameters. plungers reclprocatably mounted in said bores, saidhousing provided with suction passages for oil opening through suctionopenings into each of said bores, said suction openings being locatedpredetermined distances from the tops of the plungers in the extremesuction position, said housing provided with a discharge passageway foroil common to both of said bores, means for reciprocating said plungersso that they will cover their respective suction openings inpredetermined sequence, one of said plungers composed of adjustablyconnected sections whereby the length of the plunger may be varied forvarying the relative distances between the suction openings and the topof their respective plungers in the extreme suction positions to varythe sequence of covering of the respective suction openings.

2. In a fuel injection pump, a housing having first and second bores ofdifferent diameters. plungers reciprocatably mounted in said bores, saidhousing provided with suction passages for oil opening through suctionopenings into each of said bores, said suction openings being locatedpredetermined distances from the tops of. the plungers in the extremesuction position, said housing provided with a discharge passageway foroil common to both of said bores; means for reciprocating said plungersso that they will cover their respective suction openings inpredetel-mined sequence, the plunger mounted in the bore of the smallerdiameter being adjustable as to length to vary the relative distancesbetween the suction openings and the top of their respective plungers inthe extreme suction positions to vary the sequence of' covering of therespective suction openings.

3. In a fuel injection pump, a, housing with first and second coaxialbores -of different. diameters, plungers reciprocatably mounted in saidbores, said plungers composed of adjustably con: nected sectionsconnected for joint axial move ment in at least the discharge directionand ad-' justable to vary the distance between the tops of the'pIungers, said housing having suction passages therein opening intoeach of the bores at different distances from the effective tops oftheir plungers in the extreme suction positions, said housing providedwith a discharge passage common to both bores for the passage of oilfrom the bores.

4. In a fuel injection pump, a housing having therein a first bore and asecond bore of larger diameter than the first bore, a pilot plungerreciprocatably mounted'in the first bore, a main connected sectionsadjustable one relative to anplunger reciprocatably mounted in thesecond bore, said housing provided with passages for oil opening throughsuction openings into each of the bores, the suction opening in thefirst bore being closer to the effective top of the pilot plunger thanthe suction opening in the second bore is to the effective top of themain plunger, means for moving the plungers at such, a rate that thepilot plunger blocks its suction openingbefore the main plunger blocksits suction port and thus discharges first, said pilot plunger beingcomposed of adjustably connected sections adjustable to vary the lengthof the plunger for varying the relative distances between the suctionopenings and the top of their respective plungers in the extreme suctionpositions to vary the sequence of covering of the respective suctionopenings and means for varying the effective stroke of the main plungerfrom zero to a predetermined maximum, said housing having a dischargepassage'therein common to both bores for the passage of oil from thebores.

5. In a fuel injection pump, a housing therein first and second coaxialbores, said second bore being of larger diameter than the first bore, apilot plunger in the first bore, a main plunger in the second bore, athreaded connection between the plungers whereby they are connected forjoint axial movement and capable of axial adjustment relative to' eachother, said housing having suction passages therein opening throughsuction openings into each of the bores,

having said suction openings being arranged so that the one in the'first bore is blocked first by its plunger on the discharge stroke,said housing having a third bore therein and having a fluid passagetherein connecting said third bore to the upper portion of the secondbore, a check valve in said fiuid passage to prevent back flow into thebore, said housing having a discharge chamber therein adapted to beconnected to an engine, said housing having a passage therein connectingthe third bore to the discharge chamber, said first bore being incommunication with said chamber, and a check valve in said first borefor preventing back flow from the chamber into the bore.

6. In a fuel injection pump as claimed in claim 5, a fluid passagewayconnecting the upper portion of the second bore to the first bore andopening into the first bore between the suction opening and the secondbore, and a passageway connecting the top of the pilot plunger to anintermediate portion thereof adapted to register with said fiuidpassageway.

'7. In a fuel injection pump as claimed in claim 5, means for varyingthe effective stroke of the main plunger from zero to a predeterminedmaximum.

8. In a fuel injection pump, a housing having first and second bores ofmaterially different displacements, plungers reciprocably mounted insaid bores, said housing having suction passageways therein opening intosaid bores for deliver ing oil to the bores, said housing having adischarge passageway therein common to both of said bores for thedischarge of oil from the bores. one of said plungers being formed ofadjustably said bores, said housing having suction passageways thereinopening into said bores for deliver-.

ingoil to the bores, said housing having a discharge passageway thereincommon to both of said bores for the discharge of oil from the bores,one of said plungers comprising adjustably connected sections adjustablerelative to each other to vary the length of the plunger for varying thequantity discharge of the plunger.

10. In a fuel injection pump, a housing having therein first and secondcoaxial bores, said second bore being of larger diameter than said firstbore, a pilot plunger in the first bore, a main plunger in the secondbore, said housing having suction passages therein opening throughsuction openings into each of said bores, the suction opening in thefirst bore being closer to the effective top of the pilot plunger thanthe suction opening in the second hole is to the effective top ofthe'main plunger, means for moving the plungers at such a rate that thepilot plunger blocks its suction opening before the main plunger blocksits suction port and thus discharges first, said pilot plunger beingformed of two adjustably connected sections which may be adjustedrelative to each other to vary the discharge capacity of the pilotplunger.

11. In a fuel injection pump, a pump body having a large cylinder boreand a small cylinder bore in approximate alignment therewith, each boreprovided with a discharge passage, said pump body having a dischargepassage therein to which said cylinder bore discharge passages connect,a large plunger in said large cylinder bore, a small plunger in saidsmall cylinder bore, said body provided with passages for deliveringfuel to said small cylinder bore, and with other passages for deliveringfuel to the large cylinder bore, said passages arranged whereby uponreciprocation of the plungers said small plunger will discharge apredetermined quantity of fuel through said discharge passage prior todischarge of fuel by said large plunger, said small plunger being formedof two adjustably connected sections which may be adjusted relative toeach the other of said plungers, separate valve means for controllingthe delivery of each of said plungers and its respective cylinder, afuel delivery line communicating with each of said valve means andadapted to deliver fuel from both of said cylinders to a combustionchamber, one of said plungers and its respective cylinder being capableof effecting a portion of its injection at a time difierent than thetime of injection effected by the other of said plungers and itsrespective cylinder, one of said plungers being formed of a plurality ofadjustably connected sections which sections may be adjusted relative toeach other to vary the discharge capacity of the plunger.

GEORGE STEVEN. ROY R. FRUEHAUF.

REFERENCES CITED Number Number 10 UNITED STATES PATENTS Name DateGathmann Jan. 25, 1910 Daimler et a1 Jan. 14, 1913 Deschamps Nov. 12,1935 Gambrell Dec. 6, 1938 Bischof Sept. 19, 1939 Davis Apr. 15, 1941Links et a1. Sept. 22, 1942 FOREIGN PATENTS Country Date Switzerland1943

